textproduct: Albany

SYNOPSIS

Lake effect snow will slowly shift southward into the Mohawk Valley, Capital Region and northern Catskills today. Heavy snow accumulations are expected where the band sets up, especially across the Mohawk Valley, with light to moderate accumulations within the Capital District into western New England. Following a drier Saturday, a low pressure system will bring mixed rain and snow on Sunday with another system possibly bringing a widespread snow next Tuesday.

SHORT TERM /THROUGH SUNDAY NIGHT/

Key Messages:

- A period of lake effect snow will set up across the Mohawk Valley, Northern Catskills, Capital District and parts of western New England today. Snowfall amounts of 6 to 12 inches are expected in the most persistent lake effect bands, mainly across the Mohawk Valley. - A Lake Effect Snow Warning remains in effect for Herkimer and Hamilton Counties with Winter Weather Advisories for Fulton, Montgomery, Schoharie, eastern Rensselaer and northern Berkshire counties. - Wind gusts between 30 and 40 mph today could lead to some blowing and drifting snow.

- A low pressure system will bring mixed rain and snow on Sunday with moderate snow accumulations possible across portions of the Adirondacks.

Discussion:

An upper level trough is beginning to cross the region early this morning. A lake effect band has impacted the Adirondacks over the past several hours, mainly along and north of Route 28. As the trough crosses through the overnight, winds will shift to a more west- northwesterly direction with the band gradually sinking southward. Through the morning hours, the primary band will become oriented within the Mohawk Valley and gradually expand well inland, thanks to a multi-lake connection with Georgian Bay, into the Hudson Valley (mainly the Capital District) and portions of western New England (mainly southern Vermont into western Massachusetts). There remains some uncertainty where the band will set up exactly today as the band may only be around 15 miles wide. The scenarios continue to be either the band setting up right along the entire Thruway corridor or just to the south. Based on a disruption to the low- level wind flow, some fluctuations in the band location and intensity is expected this morning but the band could become more stationary and more intense by this afternoon. Where it does set up, expect snowfall rates to reach 1 to 2 inches per hour with near whiteout conditions at times. Snowfall accumulations will widely vary based on where the band sets up with 6-12 inches where the band becomes most persistent. Some locations within southern Herkimer County are likely to reach these totals. Some of these localized amounts could even extend into parts of Fulton, Montgomery or Schoharie counties pending band location and duration. Even snowfall amounts of 1 to 4 inches can occur within portions of the Hudson Valley (especially the Capital District) with slightly higher amounts (2 to 5 inches) for parts of the northern Taconics into western Massachusetts. Anyone traveling for the holiday weekend today in these areas should be on alert for rapidly changing weather conditions today with dry weather/pavement to near whiteout conditions occurring within just a few miles. Lake Effect Snow Warnings and Winter Weather Advisories remain in effect into tonight. Wind will also pick up today with frequent gusts between 30 and 40 mph. This could lead to some areas of blowing and drifting snow, especially where temperatures hover near or below freezing. High temperatures today will only reach the 30s except lower 40s across the mid- Hudson Valley and mid to upper 20s across the Adirondacks and southern Greens.

Wind flow will become more northwesterly tonight and weaken in intensity as the upper trough departs and surface high pressure builds in from the west. The lake effect band will begin to weaken in intensity, reduce inland extent and possibly drift farther southward overnight into more of the Catskills. Saturday will feature more clouds than sun but it will remain somewhat breezy and chilly with highs similar to today. The flow gradually shifts back to a more westerly direction where some light lake effect snow showers may linger, mainly across southern and central Herkimer County, though any additional accumulations will be little to none.

Clouds increase again Saturday night as the next low pressure system tracks across the Great Lakes. Precipitation will begin to overspread the region later Saturday night and continue through the day Sunday. Snow or a rain/snow mix to start will transition to rain or a rain/snow mix through the day Sunday. The greatest precipitation amounts are expected to occur within the southern foothills of the Adirondacks as strong southerly flow enhances upslope flow. Latest NBM probabilities for greater than 4 inches on Sunday are 50 and 80 percent within parts of the Adirondacks with less than 40 percent probabilities for greater than 7 inches. Winter Weather Advisories may be needed later in time for these areas. This flow could also lead to some downsloping effects and lower precipitation amounts for parts of the Mohawk Valley and Hudson Valley. Temperatures Sunday rise into the mid-30s to mid-40s. As the system and cold front depart, the return of cold air aloft and west to northwesterly flow will generate another round of lake effect snow showers for Sunday night into early Monday.

LONG TERM /MONDAY THROUGH THURSDAY/

Key Message:

- A low pressure system tracking south and east of the region Tuesday into Wednesday could bring a widespread snowfall with latest NBM probabilities of greater than 4 inches at 30 to 50 percent.

Discussion...

Any lake effect response will be short lived on Monday as high pressure quickly builds in overhead with drier weather. On Tuesday, a northern and southern stream shortwave will interact with one another forming a surface low near the Lower Mississippi Valley coast and track northeastward off the East Coast. While there is consensus of a track to the south and east of our region, there is some spread with how close to the coast it does track. Regardless of track, if precipitation were to occur, it would mostly be in the form of snow. A track closer to the coast would increase snowfall accumulations with a track farther off the coast likely resulting in less snow or no snow at all. Latest NBM probabilities of greater than 4 inches are between 30 and 50 percent across all of eastern New York and western New England. Will continue to monitor trends for this precipitation event. This system departs the region Tuesday night with high pressure bringing drier weather on Wednesday. Some snow showers are then possible to return by next Thursday as a cold front crosses the Great Lakes, especially for areas north and west of the Capital District. Temperatures for next week will run below normal with highs in the 20s and 30s and lows in the teens and 20s each day.

AVIATION /12Z FRIDAY THROUGH TUESDAY/

A closed upper level low is located over western Quebec. Meanwhile, the large upper level trough is located over the eastern Great Lakes and extending eastward into the Northeast, with the trough axis currently extending across west-central NY and central PA. This trough axis will be swinging across the region for today.

Bands of lake effect snow are currently ongoing off Lake Erie and Lake Ontario, but the current flow is keeping these bands west and northwest of the region at this time. Still, the cyclonic flow in place is allowing for widespread bkn-ovc stratocu, with ceilings around 4-6 kft and VFR conditions. West to southwest winds will be around 10 kts to start the day.

During the morning hours today, the flow aloft will be changing to more west to west-northwest as the trough axis pushes eastward. This will allow the band off Lake Ontario to shift southward. Some light snow showers from this band may reach KGFL by 13z-17z, allowing for brief periods of IFR visibility within snow showers. Most of the snow should be south of KGFL by 18z.

Meanwhile, a few flurries or passing snow showers are possible near KALB as early as 15z, but the main threat for the true lake effect band will be around 19z-00z, when brief bursts of moderate-heavy snowfall will be possible, allowing for IFR visibility. Similar timing is expected for KPSF (20z-02z). Meanwhile, snow showers should stay north of KPOU through the entire day. Some lingering flurries or snow showers could continue into tonight for KALB/KPSF, but the steadiest activity should be over by that point. A quick inch or two may accumulate within the lake effect snow activity.

Winds will be gusty today, especially from mid-morning onward. Sustained winds from the west will be around 15 kts, with frequent gusts in the 20-30 kt range. A few gusts may exceed 30 kts, mainly for KALB/KPSF during the afternoon hours. Winds will diminish slightly for tonight but still will remain rather breezy.

Outlook...

Saturday Night: Low Operational Impact. Slight Chance of SN. Sunday: High Operational Impact. Breezy. Definite RA...SN. Sunday Night: Moderate Operational Impact. Chance of SHRA...RA. Monday: No Operational Impact. NO SIG WX. Monday Night: Low Operational Impact. NO SIG WX. Tuesday: Moderate Operational Impact. Chance of RA...SN. Tuesday Night: Moderate Operational Impact. Chance of SN. Wednesday: No Operational Impact. NO SIG WX.

ALY WATCHES/WARNINGS/ADVISORIES

CT...None. NY...Winter Weather Advisory from 10 AM this morning to 10 PM EST this evening for NYZ054. Lake Effect Snow Warning until 1 AM EST Saturday for NYZ032- 033. Lake Effect Snow Warning until 7 AM EST Saturday for NYZ038. Winter Weather Advisory until 7 AM EST Saturday for NYZ039-040- 047-082. MA...Winter Weather Advisory from 10 AM this morning to 10 PM EST this evening for MAZ001. VT...None.